Yamaha 50H Outboard Motor Review

Originally published in TrailerBoat #274, September / October 2011.

I never knew that Yamaha still had a manual-start version of its long-running 50H Tiller Steer outboard motor — until I tried one last year. Originally released on the Australian market in 1985, this was the engine from which Yamaha developed its 40V.

YAMAHA 50H

The Yamaha 40 has a 2:1 gear ratio and the 60 has a hefty 2.33:1 ratio; the Yamaha 50H, however, has a recreationally-orientated 1.85:1 ratio, which loses a fair amount of thrust efficiency when pushing loads at displacement speeds. Still, for tiller-steer planing hulls the taller ratio does reduce prop-steer torque when planing, whereas the Yamaha Enduro 60 really builds up your arm muscles.

Having three cylinders, the 698cc Yamaha 50H is much easier to start than the 703cc twin-cylinder Enduro 40. It also idles and trolls more smoothly, whereas the 40 tends to shake your teeth out below 2000rpm. At 80kg the 50H is 7kg heavier than the single-carbie Enduro 40, but 22kg lighter than the 849cc three-cylinder Enduro 60 which, like the 50H, has three carbies.

Of course, the Yamaha 50H is up-rated from its 40V counterpart whereas the Yamaha 60 is de-rated from its 70B counterpart, so it develops at lot more torque. The Yamaha 50H develops 49.3hp at 5000rpm with a WOT (Wide Open Throttle) rpm range of 4500 to 5500, and in shortshaft form has been very popular with owners of Thundercats.

ON THE WATER

I was recently at Mitchells Island on the Manning River near Taree, NSW, reviewing a prototype of a new 5m foam sandwich fishing boat. Nigel, the owner, had a lifetime’s experience building inboard timber launches and this particular boat — a Fission 500 as he called it — was powered by a manual-start Yamaha 50H.

The engine had already had a hard life on an oyster punt before Nigel acquired it, and it hadn’t been run for almost a year before the test. Consequently, the fuel was a bit stale, but after a couple of tugs of the recoil starter the engine roared to life. Despite extended idling periods between performance trials, the engine didn’t miss a beat. It was only after 15 minutes or more of idling and trolling that oil smoke started to appear on the post break-in (10 hours on 25:1) mix of unleaded petrol and oil (make unknown) at 50:1.

The long multifunction tiller arm with upfront gearshift was a delight to use, especially as the review hull had a helm seat mounted to starboard, situated just ahead of the Yammie. Similarly, the gas-assist tilt cylinder made tilting the engine a very easy task.

Providing the anti-ventilation plate was kept immersed, power astern was good and no cooling water starvation occurred.

The Fission 500 is unusual in that it has a broad 2.3m beam and gull-wing chines, creating tunnels either side of the centreline which taper as they reach the transom. Combined with a broad, flat-planing plank the hull not only planes easily but floats in very shallow water.

Spinning a well-worn 12in-pitch Yamaha alloy prop and pushing a total of 700kg including three adults, the 50H planed easily. Despite having a performance-robbing hydrofoil (I really hate those gimmicks) on the anti-ventilation plate, the Yammie returned very good cruising and WOT speeds. In fact, I estimate that we would have pulled another 300-400rpm at WOT, and gone around 1.8kts (3.3kmh) faster, if it weren’t for the foil.

Through full-lock figure-of-eight turns at two-thirds throttle absolutely no prop ventilation occurred. Across the entire rpm range vibration levels were very low, and the 50H was only raucous at or near WOT due to carbie induction roar.

SERVICING AND MAINTENANCE

Servicing the Yamaha 50H is straightforward, and Yamaha recommends doing so every 100 hours or annually after the 20-hour service. Providing this is performed by an authorised Yamaha dealer the recreational usage warranty is three years.

PRICE

The Yamaha 50H has a proven reputation for reliability. Since Yamaha introduced YDC30 titanium-blend alloy in the ’90s it also enjoys excellent saltwater corrosion resistance. It’s a gutsy, easily maintained and affordable outboard which suits the needs of saltwater anglers on a tight budget, as well as those who realise that fuel costs are only a small part of the expenses of running a recreational outboard. As of June 2011 the manual longshaft Yamaha 50H had a price of $5954 RRP, with a spare alloy prop costing $130.

YAMAHA 50H PERFORMANCE

COMPETING OUTBOARDS

* The Mercury Sea Pro 55 is a de-rated 60 whereas the Tohatsu M50D2L is up-rated from the M40D.